From: Kedar Mhaswade <kedar.mhaswade@...>
Date: 2011-01-25T10:41:54+09:00
Subject: Is an instance of a class really an instance of its superclass too?

I understand that the answer to that question is yes.

But then a singleton class (using require 'singleton') can have two or
more instances in a Ruby program, like:

require 'singleton'

class Super
  include Singleton
end
class Sub < Super
end

puts Super.instance
puts Sub.instance

#=> <Super:0x000000024b5648>
#=> <Sub:0x000000024b55d0>

Doesn't this mean we have two instances of a class (Super) whose only
one instance should have been in the program (because the class included
'singleton')? IOW, shouldn't class Sub < Super be disallowed?

Thanks,
Kedar

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